1. Field of the Invention:
The present invention relates generally to printing apparatus, and more particularly, to a drum and saddle type apparatus having a magnetic lockup assembly along one edge of a printing plate.
2. Description of the Prior Art:
In the past, print plates for rotary printing presses have typically been of two types. In one type, a thin flexible printing plate is directly mounted on the surface of a cylinder drum and the edges of the plate are fastened by various means into recesses in the drum. In a second type, one or more cylindrically shaped saddles are mounted on the surface of the drum with spaces between the saddles for inserting the lockup mechanism which holds the printing plate onto the surface of the saddle. Typically, the edges of the saddles are beveled inwardly and at least one edge of the printing plate is bent inwardly to engage the beveled edge in the recess between the saddles. The opposite edge of the printing plate has been formed in many different configurations to cooperate with various mechanical lockup mechanisms which engage the other edge of the plate and apply some tension to securely mount the plate on the saddles. The saddle technique greatly increases the versatility of the roller printing presses in that saddles and lockup mechanisms may be replaced or changed without removing the drum from the press. While there are many types of lockup mechanisms for printing plates, almost all require some kind of mechanical actuation by the workman in order to insert or remove a plate. Typically, this means operating in very close spaces with great possibility of injury to the workman or marring the printing plate due to excessive handling. Additionally, the lockup mechanisms are usually relatively complicated mechanically and expensive to both maintain and to originally construct.
Thus, there has been a need in the field of saddle lockup techniques which is simple mechanically and requires a minimum of operation by the workman in locking or unlocking a printing plate over a saddle. The present invention satisfies that need.